A machine of this kind is known from German Patent 3710517 and German Patent 3819257.
German Patent 3710517 describes a washing machine for cleaning endoscopes having a conduit for cleaning fluid that can be connected to the proximal end of a working channel of the endoscope. This conduit feeds cleaning fluid coming from a circulating pump directly to the working channel. This publication also describes how a pressure differential can be generated for the cleaning fluid flowing along the outer wall of the endoscope. The endoscope tube is conducted in a hollow tube that is longer than the endoscope tube so that a flow separation occurs at the distal end of the endoscope tube, which generates a vacuum that exercises a suction effect in the cleaning fluid flowing through the working channel.
German Patent 3819257 shows a similar machine in which the endoscope head is inserted into a receptacle which is pressurized by the cleaning fluid coming from the circulating pump of the machine.
The different channels in today's endoscopes are becoming narrower and narrower because increasingly more functions are accommodated while the diameter of the endoscope remains essentially the same. For example, these endoscopes have a so-called "Albarran channel" a working channel in which a cable-pull is conducted. This channel is so narrow that the annular gap between the cable-pull and the channel is only 0.1 mm or less. Cleaning and disinfection of such narrow channels can be carried out satisfactorily if at all only over a very long time. Naturally, it would be possible in principle to provide the machines known from the aforementioned publications with an additional feed pump, this pump for a higher pressure being connected to the working channels of the endoscope. This approach would be expensive, however, and is therefore rejected.